Plasma processing method and apparatus and tray for plasma processing

ABSTRACT

Provided is a plasma processing method and apparatus and a tray for plasma processing, which are able to improve the temperature controllability of a substrate. If a vacuum chamber is evacuated by a pump while introducing a specified gas by a gas supply unit into the vacuum chamber and a high-frequency power is applied by a coil use high-frequency power supply to a coil while maintaining the interior of the vacuum chamber to a specified pressure, then plasma is generated in the vacuum chamber, and a substrate placed on a substrate electrode can be subjected to plasma processing. At this time, by providing an adhesive sheet between the substrate electrode and the substrate, the temperature controllability of the substrate can be improved.

BACKGROUND OF THE INVENTION

[0001] The present invention relates to a plasma processing method and apparatus and a tray for plasma processing to be utilized for manufacturing electronic devices, micro machines (MEMS: Micro Electromechanical Systems), boards for mounting components, and so on.

[0002]FIG. 19 shows one example of a generic parallel plate type plasma processing apparatus.

[0003] Referring to FIG. 19, if a vacuum chamber 201 is evacuated by a pump 203 as an exhauster while introducing a specified gas by a gas supply unit 202 into the vacuum chamber 201 and high-frequency power of 13.56 MHz is applied to a substrate electrode 206 by a substrate electrode high-frequency power supply 210 while maintaining the interior of the vacuum chamber 201 to a specified pressure by a pressure-regulating valve 204, then plasma is generated in the vacuum chamber 201, and a substrate 209 placed on the substrate electrode 206 can be subjected to plasma processing of etching, deposition, surface reforming, or the like. The turbo-molecular pump 203 and an exhaust port 211 are disposed just under the substrate electrode 206, and the pressure-regulating valve 204 is an up-and-down valve disposed just under the substrate electrode 206 and just over the turbo-molecular pump 203. The substrate electrode 206 is fixed to the vacuum vessel 201 with four props 212. Moreover, an opposite electrode 241 is provided oppositely to the substrate electrode 206.

[0004] As another plasma processing apparatus, there is a plasma processing apparatus of a high-frequency induction system for generating plasma in the vacuum vessel by applying high-frequency power to a coil. The plasma processing apparatus of this system, which generates plasma by generating a high-frequency magnetic field in the vacuum vessel and accelerating electrons by generating an inductive electric field inside the vacuum vessel by its high-frequency magnetic field, is able to generate plasma of a density higher than the parallel plate type plasma.

[0005]FIG. 20 shows one example of the construction. Referring to FIG. 20, by evacuating a vacuum chamber 201 by a turbo-molecular pump 203 as an exhauster while introducing a specified gas from a gas supply unit 202 into the vacuum vessel 201 and by applying high-frequency power of 13.56 MHz to a coil provided along a dielectric plate 207 opposite to a substrate electrode 206 by a coil use high-frequency power supply 205 while maintaining the interior of the vacuum vessel 201 to a specified pressure by a pressure-regulating valve 204, then inductive-coupling type plasma is generated in the vacuum vessel 201, and a substrate 209 placed on the substrate electrode 206 can be subjected to plasma processing.

[0006] There is also provided a substrate-electrode use high-frequency power supply 210 for supplying high-frequency power to the substrate electrode 206, making it possible to control ion energy that reaches the substrate 209. The turbo-molecular pump 203 and the exhaust port 211 are disposed just under the substrate electrode 206, and the pressure-regulating valve 204 is an up-and-down valve disposed just under the substrate electrode 206 and just over the turbo-molecular pump 203. The substrate electrode 206 is fixed to the vacuum vessel 201 with four props 212.

[0007] Up to now, various materials have been used as the surface material of the substrate electrode. Besides metals such as aluminum and stainless steel, there have been an example in which only a part of the surface of a substrate electrode is covered with an insulating layer (hard alumite) and only the insulating layer is brought in contact with a substrate as disclosed in U.S. Pat. No. 2,758,755, an example in which a substrate electrode portion to be brought in contact with a substrate is covered with a dielectric film (vinyl chloride, Teflon (the registered trademark of U.S. Dupont of Polytetrafluoroethylene resin mold), or polyimide) as disclosed in Japanese Laid-Open Patent Publication No. 2-155230, an example in which a substrate electrode portion to be brought in contact with a substrate is covered with a dielectric film constructed of at least one of vinyl chloride, Teflon, and polyimide, and the self-bias voltage of the substrate electrode is monitored to detect the damage of the dielectric film as disclosed in U.S. Pat. No. 3,010,683, and so on. As described above, if a dielectric layer is provided between the substrate and the substrate electrode, there is an effect of reducing the charge-up damage.

[0008] There is another method for improving the thermal conduction of a substrate and a substrate electrode by covering the surface of the substrate electrode with a ceramic layer and applying a DC voltage to a DC electrode buried in the ceramic layer for the suction of the substrate onto the substrate electrode surface with an electrostatic force or for the pressing of the substrate against the substrate electrode by a clamp ring. There is also a method for improving the thermal conduction of a substrate and a substrate electrode by supplying gas (helium or the like), which becomes a thermal medium, between the substrate and the substrate electrode.

[0009] However, the aforementioned conventional system has had an issue that, if it has been attempted to process a thin soft substrate (resin sheet, for example), the temperature of the substrate has disadvantageously been raised by plasma exposure.

[0010] This is attributed to the fact that the heat exchange between the substrate and the substrate electrode becomes insufficient in a vacuum in addition to the small thermal capacity of the substrate. If it is attempted to suck the substrate onto the substrate electrode surface with an electrostatic force, then a direct current scarcely flows through a dielectric substrate, and the suction cannot takes effect. Moreover, if gas that becomes a thermal medium is supplied between the substrate and the substrate electrode with the substrate pressed against the substrate electrode by a clamp ring, the substrate is significantly deformed because the substrate is thin and soft. This not only impairs the uniformity of processing but also possibly generates abnormal discharge in a space formed between the substrate and the substrate electrode, lacking practicability.

[0011] Moreover, if gas that becomes a thermal medium is supplied between the substrate and the substrate electrode when the substrate is large, thin, hard, and easy to break (silicon, glass, ceramics, or the like) in the conventional system, then the substrate significantly deforms because the substrate is thin, and the substrate sometimes breaks. Particularly, when the substrate thickness is not greater than 1 mm and the area is not smaller than 0.1 m², the aforementioned issue sometimes occurs.

SUMMARY OF THE INVENTION

[0012] In view of the aforementioned conventional issues, it is an object of the present invention to provide a plasma processing method and apparatus and a tray for plasma processing, which are able to improve the temperature controllability of a substrate.

[0013] In order to achieve the aforementioned object, the present invention is constructed as follows.

[0014] According to a first aspect of the present invention, there is provided a plasma processing method comprising:

[0015] evacuating inside of a vacuum chamber and supplying gas into the vacuum chamber and the generating plasma in the vacuum chamber while controlling interior of the vacuum chamber to a specified pressure; and

[0016] processing a substrate or a film on a substrate placed on a substrate electrode in the vacuum chamber while carrying out heat exchange between the substrate and the substrate electrode via an adhesive sheet disposed between the substrate electrode and the substrate.

[0017] According to a second aspect of the present invention, there is provided a plasma processing method comprising:

[0018] evacuating inside of a vacuum chamber and supplying gas into the vacuum chamber and then generating plasma in the vacuum chamber while controlling interior of the vacuum chamber to a specified pressure; and

[0019] processing a substrate or a film on a substrate on a tray placed on a substrate electrode in the vacuum chamber while carrying out heat exchange between the tray and the substrate via an adhesive sheet disposed between the tray and the substrate.

[0020] According to a third aspect of the present invention, there is provided the plasma processing method as defined in the second aspect, wherein the substrate or the film on the substrate is processed while carrying out heat exchange between the substrate electrode and the tray via the adhesive sheet disposed between the substrate electrode and the tray.

[0021] According to a fourth aspect of the present invention, there is provided a plasma processing method comprising:

[0022] transporting a substrate into a vacuum chamber;

[0023] holding the substrate while deforming the substrate in a convex shape toward a substrate electrode in the vacuum chamber;

[0024] bringing a neighborhood of a center portion of the substrate deformed in the convex shape in contact with an adhesive sheet provided on a surface of the substrate electrode;

[0025] bringing almost an entire one surface of the substrate in contact with the adhesive sheet provided on the surface of the substrate electrode; and

[0026] processing the substrate or a film on the substrate by evacuating inside of the vacuum chamber and supplying gas into the vacuum chamber and then generating plasma in the vacuum chamber while controlling interior of the vacuum chamber to a specified pressure.

[0027] According to a fifth aspect of the present invention, there is provided a plasma processing method comprising:

[0028] transporting a substrate into a vacuum chamber;

[0029] holding the substrate above a convex substrate electrode in the vacuum chamber;

[0030] bringing a neighborhood of a center portion of the substrate in contact with an adhesive sheet provided on a surface of the substrate electrode;

[0031] bringing almost an entire one surface of the substrate in contact with the adhesive sheet provided on the surface of the substrate electrode by pressing an outer edge portion of the substrate against the substrate electrode; and

[0032] processing the substrate or a film on the substrate by evacuating inside of the vacuum chamber and supplying gas into the vacuum chamber and then generating plasma in the vacuum chamber while controlling interior of the vacuum chamber to a specified pressure.

[0033] According to a sixth aspect of the present invention, there is provided a plasma processing method comprising:

[0034] bringing almost and entire one surface of a substrate in contact with an adhesive sheet provided on a surface of a tray;

[0035] transporting the tray into a vacuum chamber;

[0036] holding the tray above a substrate electrode in the vacuum chamber;

[0037] placing the tray on the substrate electrode; and

[0038] processing the substrate or a film on the substrate by evacuating inside of the vacuum chamber and supplying gas into the vacuum chamber and then generating plasma in the vacuum chamber while controlling interior of the vacuum chamber to a specified pressure.

[0039] According to a seventh aspect of the present invention, there is provided the plasma processing method as defined in the first aspect, wherein the adhesive sheet has a thermal conductivity of not smaller than 0.1 W/m·K.

[0040] According to an eighth aspect of the present invention, there is provided the plasma processing method as defined in the first aspect, wherein the adhesive sheet has Asker C of not greater than 80.

[0041] According to a ninth aspect of the present invention, there is provided the plasma processing method as defined in the first aspect, wherein the adhesive sheet has a hardness of 50 to 60.

[0042] According to a 10th aspect of the present invention, there is provided the plasma processing method as defined in the first aspect, wherein the adhesive sheet has a thickness of 0.05 to 0.5 mm.

[0043] According to an 11th aspect of the present invention, there is provided the plasma processing method as defined in the first aspect, wherein the substrate is made of glass or ceramics.

[0044] According to a 12th aspect of the present invention, there is provided the plasma processing method as defined in the first aspect, wherein the substrate is a resin sheet.

[0045] According to a 13th aspect of the present invention, there is provided the plasma processing method as defined in the first aspect, wherein the substrate has a thickness of 0.001 to 1 mm.

[0046] According to a 14th aspect of the present invention, there is provided the plasma processing method as defined in the first aspect, wherein the substrate has a thickness of 0.001 to 0.5 mm.

[0047] According to a 15th aspect of the present invention, there is provided the plasma processing method as defined in the first aspect, wherein, assuming that the substrate has a Young's modulus E (Pa), the substrate has a Poisson's ratio ν, the substrate has a characteristic length a (m) and the substrate has a thickness h (m), then there holds an expression: 600×(1−ν²)a⁴/(256×Eh³)>0.005 (m).

[0048] According to a 16th aspect of the present invention, there is provided a plasma processing apparatus comprising:

[0049] a vacuum chamber;

[0050] a gas supply unit for supplying gas into the vacuum chamber;

[0051] an exhausting unit for exhausting interior of the vacuum chamber;

[0052] a pressure-regulating valve for controlling the interior of the vacuum chamber to a specified pressure;

[0053] a substrate electrode for placing thereon a substrate in the vacuum chamber;

[0054] a high-frequency power supply capable of supplying a high-frequency power to the substrate electrode or a plasma source; and

[0055] an adhesive sheet, which is disposed on a surface of the substrate electrode and on which the substrate is placed.

[0056] According to a 17th aspect of the present invention, there is provided a plasma processing apparatus comprising:

[0057] a substrate mounting station for placing a substrate on a tray having a surface provided with an adhesive sheet;

[0058] a vacuum chamber;

[0059] a gas supply unit for supplying gas into the vacuum chamber;

[0060] an exhausting unit for exhausting interior of the vacuum chamber;

[0061] a pressure-regulating valve for controlling the interior of the vacuum chamber to a specified pressure;

[0062] a substrate electrode for placing thereon the tray in the vacuum chamber; and

[0063] a high-frequency power supply capable of supplying a high-frequency power to the substrate electrode or a plasma source.

[0064] According to an 18th aspect of the present invention, there is provided the plasma processing apparatus as defined in the 16th aspect, wherein the adhesive sheet has a thermal conductivity of not smaller than 0.1 W/m·K.

[0065] According to a 19th aspect of the present invention, there is provided the plasma processing apparatus as defined in the 16th aspect, wherein the adhesive sheet has Asker C of not greater than 80.

[0066] According to a 20th aspect of the present invention, there is provided the plasma processing apparatus as defined in the 16th aspect, wherein the adhesive sheet has a hardness of 50 to 60.

[0067] According to a 21st aspect of the present invention, there is provided the plasma processing apparatus as defined in the 16th aspect, wherein the adhesive sheet has a thickness of 0.05 to 0.5 mm.

[0068] According to a 22nd aspect of the present invention, there is provided a tray for plasma processing used for plasma processing for processing a substrate or a film on the substrate, comprising:

[0069] an adhesive sheet disposed on a surface on which the substrate is placed.

[0070] According to a 23rd aspect of the present invention, there is provided the tray for plasma processing as defined in the 22nd aspect, comprising:

[0071] another adhesive sheet disposed on a surface opposite from the surface on which the substrate is placed.

[0072] According to a 24th aspect of the present invention, there is provided the tray for plasma processing as defined in the 22nd aspect, wherein the adhesive sheet has a thermal conductivity of not smaller than 0.1 W/m·K.

[0073] According to a 25th aspect of the present invention, there is provided the tray for plasma processing as defined in the 22nd aspect, wherein the adhesive sheet has Asker C of not greater than 80.

[0074] According to a 26th aspect of the present invention, there is provided the tray for plasma processing as defined in the 22nd aspect, wherein the adhesive sheet has a hardness of 50 to 60.

[0075] According to a 27th aspect of the present invention, there is provided the tray for plasma processing as defined in the 22nd aspect, wherein the adhesive sheet has a thickness of 0.05 to 0.5 mm.

BRIEF DESCRIPTION OF THE DRAWINGS

[0076] These and other aspects and features of the present invention will become clear from the following description taken in conjunction with the preferred embodiments thereof with reference to the accompanying drawings, in which:

[0077]FIG. 1 is a sectional view showing the construction of a plasma processing apparatus used by a plasma processing method according to a first embodiment of the present invention;

[0078]FIGS. 2A, 2B and 2C are sectional views showing processes for placing a substrate on a substrate electrode according to the plasma processing method of the first embodiment of the present invention;

[0079]FIGS. 2D and 2E are plan views of different modification examples of the substrate electrode according to the plasma processing method of the first embodiment of the present invention;

[0080]FIGS. 3A, 3B and 3C are sectional views showing processes for placing the substrate on the substrate electrode according to the plasma processing method of the first embodiment of the present invention;

[0081]FIGS. 4A, 4B and 4C are sectional views showing processes for placing the substrate on the substrate electrode according to the plasma processing method of the first embodiment of the present invention;

[0082]FIG. 5 is a sectional view showing the construction of a plasma processing apparatus used by a plasma processing method according to a second embodiment of the present invention;

[0083]FIG. 6 is a sectional view showing the construction of the plasma processing apparatus used by the plasma processing method of the second embodiment of the present invention;

[0084]FIGS. 7A and 7B are sectional views showing processes for placing a tray on a substrate electrode according to the plasma processing method of the second embodiment of the present invention;

[0085]FIGS. 8A, 8B and 8C are sectional views showing processes for placing the tray on the substrate electrode according to the plasma processing method of the second embodiment of the present invention;

[0086]FIG. 9 is a plan view showing the overall construction of the plasma processing apparatus used by the plasma processing method of the second embodiment of the present invention;

[0087]FIG. 10 is a sectional view showing the operation of an atmospheric arm and a cassette according to the plasma processing method of the second embodiment of the present invention;

[0088]FIGS. 11A, 11B, 11C, 11D and 11E are sectional views showing a procedure for sticking an adhesive sheet to a tray according to the plasma processing method of the second embodiment of the present invention;

[0089]FIGS. 12A, 12B, 12C, 12D and 12E are sectional views showing a procedure for sticking the adhesive sheet to the tray according to the plasma processing method of the second embodiment of the present invention;

[0090]FIG. 13 is a perspective view of the tray according to the plasma processing method of the second embodiment of the present invention;

[0091]FIGS. 14A, 14B and 14C are sectional views showing processes for placing a substrate on a tray according to the plasma processing method of the second embodiment of the present invention;

[0092]FIGS. 15A, 15B and 15C are sectional views showing processes for placing the substrate on the tray according to the plasma processing method of the second embodiment of the present invention;

[0093]FIGS. 16A, 16B and 16C are sectional views showing processes for placing the substrate on the tray according to the plasma processing method of the second embodiment of the present invention;

[0094]FIGS. 17A, 17B and 17C are sectional views showing processes for placing the substrate on the tray according to the plasma processing method of the second embodiment of the present invention;

[0095]FIG. 18 is a sectional view showing the construction of a tray according to one embodiment of the present invention;

[0096]FIG. 19 is a sectional view showing the construction of a plasma processing apparatus used in a prior-art example;

[0097]FIG. 20 is a sectional view showing the construction of a plasma processing apparatus used in a prior-art example;

[0098]FIG. 21 is a partially sectional explanatory view of the case where an adhesive sheet has through holes in a modification example of the embodiment of the present invention;

[0099]FIG. 22 is a partially sectional explanatory view of the case where an adhesive sheet has grooves in a modification example of the above embodiment of the present invention;

[0100]FIGS. 23A, 23B, 23C and 23D are explanatory views of adhesive sheets of various modification examples of the above embodiment of the present invention;

[0101]FIGS. 24A, 24B and 24C are an explanatory view for explaining a state in which an adhesive sheet is disposed with interposition of a gap on a recess portion of a substrate electrode in the above embodiment of the present invention, an explanatory view for explaining a state in which the adhesive sheet enters the gap as a consequence of the pressing of the adhesive sheet together with the substrate by a clamp ring, and an explanatory view for explaining a state in which an adhesive sheet is disposed without interposition of a gap on the recess portion of a substrate electrode, respectively, in the above embodiment of the present invention;

[0102]FIGS. 25A, 25B and 25C are explanatory views of a case where an adhesive sheet is transported together with a substrate in a modification example of the above embodiment of the present invention;

[0103]FIG. 26 is an explanatory view of a case where an adhesive sheet is constructed of two layers in a modification example of the above embodiment of the present invention;

[0104]FIG. 27 is an explanatory view for explaining a state in which a substrate is placed on an adhesive sheet of a tray and thereafter a roller is rotated on the substrate in a modification example of the above embodiment of the present invention; and

[0105]FIG. 28 is an explanatory view for explaining a case where exhaust holes are provided only in a center portion of a tray in a modification example of the above embodiment of the present invention;

[0106]FIGS. 29A, 29B, 29C, and 29D are a front view of a spring type hardness tester of type A or type C, a rear view of the tester with a rear lid thereof removed, an enlarged view of an indentor tip thereof, and a partial sectional view of the tester showing relationship between an indentor thereof and a pressing surface thereof, for explaining Asker C;

[0107]FIGS. 30A and 30B are graphs each showing a distance between the pressing surface and the indentor tip, a load applied to the indentor tip by the spring, and the scale, in order to show reference lines indicating relationship among the scale, the movement of the indentor, and the spring force thereof;

[0108]FIG. 31 is a cross-sectional view of the case where an adhesive sheet is placed on an uneven surface defined by plural resin tapes and a substrate electrode in another modification example of the above embodiment of the present invention;

[0109]FIG. 32 is an enlarged view of a circle portion III in FIG. 31; and

[0110]FIG. 33 is a plane view of the case of FIG. 31 before the adhesive sheet is placed on the uneven surface.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0111] Before the description of the present invention proceeds, it is to be noted that like parts are designated by like reference numerals throughout the accompanying drawings.

[0112] Embodiments of the present invention will be described in detail below on the basis of the drawings.

[0113] (First Embodiment)

[0114] A first embodiment of the present invention will be described below with reference to FIGS. 1 through 4C.

[0115]FIG. 1 shows a sectional view of a plasma processing apparatus used in the first embodiment of the present invention.

[0116] Referring to FIG. 1, by evacuating a vacuum vessel 1 as one example of the vacuum chamber by a turbo-molecular pump 3 as an exhauster while introducing a specified gas from a gas supply unit 2 into the vacuum vessel 1 and by applying high-frequency power of 13.56 MHz to a coil 8 (one example of the plasma source) provided along a dielectric plate 7 opposite to a substrate electrode 6 by a coil use high-frequency power supply 5 while maintaining the interior of the vacuum vessel 1 to a specified pressure by a pressure-regulating valve 4, then inductive-coupling type plasma is generated in the vacuum vessel 1, and a substrate 9 placed on the substrate electrode 6 can be subjected to plasma processing.

[0117] In this specification and the claims, the substrate 9 means a thin soft substrate and means, for example, an object such that a circuit(s) is formed on a resin sheet (for example, sheet of polyimide), paper, or the like.

[0118] There is also provided a substrate-electrode use high-frequency power supply 10 for supplying high-frequency power to the substrate electrode 6, making it possible to control ion energy that reaches the substrate 9. The turbo-molecular pump 3 and an exhaust port 11 are disposed just under the substrate electrode 6, and the pressure-regulating valve 4 is an up-and-down valve disposed just under the substrate electrode 6 and just over the turbo-molecular pump 3. The substrate electrode 6 is fixed to the vacuum vessel 1 with four props 12. The operations of the gas supply unit 2, the coil use high-frequency power supply 5, the substrate-electrode use high-frequency power supply 10, the turbo-molecular pump 3, and the pressure-regulating valve 4 are controlled by a control unit 1000. It is to be noted that the control unit 1000 is similar in other embodiments. Therefore, it is representatively shown only in FIG. 1 and is principally omitted in the figures of the other embodiments.

[0119] An adhesive sheet 13 is provided between the substrate electrode 6 and the substrate 9, making it possible to carry out the processing while effecting heat exchange between the substrate 9 and the substrate electrode 6 via the adhesive sheet 13.

[0120] As one example of the adhesive sheet 13, a silicone rubber film is employed. The adhesive sheet 13 has self-adhesion (self-tack property) in its sheet material itself. The adhesive sheet 13 is preferably to be able to be prevented from deteriorating due to plasma during the plasma processing by having a size slightly smaller than that of the substrate 9 or, for example, at least about 1 mm or more smaller than the outer periphery. This adhesive sheet 13 has a thermal conductivity of 0.2 W/m·K, Asker C of 60, hardness of 55, and a thickness of 0.2 mm.

[0121] It is to be noted that Asker C (ASKER C) is an index of the softness of resin, and the fact that Asker C is 60 means that a value measured by an Asker C hardness meter is 60. The greater the number, the harder the material is, conversely to the penetration and consistency test.

[0122] The Asker C means the spring type Asker C type of the standard 0101 of The Society of Rubber Industry, Japan standards (SRIS), and the following measurement method is provided by K6301 (1995) (physical testing method of vulcanized rubber) of Japanese Industrial Standards (JIS).

[0123] Spring Type Hardness Test (Type A and Type C)

[0124] In principle, a specimen having a thickness of not smaller than 12 mm is used according to the type A, and specimens each having a thickness smaller than 12 mm are stacked to secure a thickness of not smaller than 12 mm as much as possible. According to the type C, a specimen having a thickness of not smaller than 6 mm is used, and specimens each having a thickness smaller than 6 mm are stacked to secure a thickness of not smaller than 6 mm as much as possible.

[0125] Moreover, the surface to be measured of the specimen is polished to become smooth when the surface is not smooth. The surface to be measured is required to have a size such that the pressing surface of the tester is required to have a size that falls at least within the surface to be measured.

[0126] With regard to the tester, a spring type hardness tester of type A or type C shown as one example in FIGS. 29A and 29B is used. This tester indicates, as hardness on a scale 303, the travel distance of the indentor 301 (see FIG. 29C), which is protruded from a hole 300 a located at the center of the pressing surface 300 by a spring pressure and is pushed back by the rubber surface of the specimen when the pressing surface 300 is brought in contact with the surface of the specimen. The pressing surface 300 is a surface perpendicular to the indentor 301 and has the hole 300 a through which the indentor 301 is put at its center as shown in FIG. 29D. The hole diameter must be not smaller than 10 mm. The tolerance of a reference line (see FIGS. 30A and 30B), which shows relations between the scale 303, the movement of the indentor 301, and the spring force, is assumed to be ±0.0785N{±8gf} in the case of type A and ±0.196N{±20gf} in the case of type C. Moreover, no play is accepted between the movement of the indentor 301 and the movement of the indicator 302. The material of the indentor 301 is wear-resistant and rust-resistant, and its configuration and dimensions are as shown in FIGS. 29C and 29D. The indentor 301 must be correctly attached to the center of the hole 300 a of the pressing surface 300. The indentor tip must protrude from the pressing surface 300 by 2.54⁰ _(−0.05) mm at 0 on the scale 303. The indentor tip surface must be located on the same plane as the pressing surface 300 at 100 on the scale 303. The scale 303 is graduated at equal intervals from 0 to 100.

[0127] Moreover, in order to effectively prevent the occurrence of a gap or foams between the adhesive sheet 13 and the substrate 9, mutually communicating through holes 13 h or grooves 13 g for allowing foams to easily escape may be formed in the adhesive sheet 13 as shown in FIG. 21 or FIG. 22. Moreover, regarding the manner of arranging the grooves 13 g, the grooves may be linearly arranged mutually parallel as shown in FIG. 23A, arranged in a grating-like form as shown in FIG. 23B, arranged radially as shown in FIG. 23C, or arranged between numbers of projecting portions 13 j as shown in FIG. 23D.

[0128]FIGS. 2A through 2C show processes for placing a polyimide resin substrate 9, which has on its surface a 300-nm thick silicon oxide film patterned by photoresist and has a thickness h=0.4 mm=0.0004 m, on the substrate electrode 6. It is to be noted that the substrate has a Young's modulus E of 3 GPa, a Poisson's ratio ν of 0.3, a circular substrate configuration, and a diameter a of 0.15 m.

[0129] First of all, the substrate 9 is transported from an opening-and-closing gate 22 of the vacuum vessel 1 into the vacuum vessel 1 by means of a transportation arm 23, and thereafter, the substrate 9 is held by a plurality of lift pins 14 (one example of the support member) (FIG. 2A). At this time, the plurality of lift pins 14 that move up and down inside through holes 6 a provided for the substrate electrode 6 are provided in the vicinity of the outer peripheral portion of the substrate electrode 6, and therefore, the substrate 9 is deformed in a convex shape protruding toward the substrate electrode 6. The plurality of lift pins 14 (for example, four pins as shown in FIG. 2D or three pins as shown in FIG. 2E) are arranged in point symmetry with respect to the center of the substrate 9. The lower ends of the plurality of lift pins 14 are fixed to a drive ring 100, and the drive ring 100 is driven to move up and down by an air cylinder 101 or the like as one example of the drive unit under the control of the control unit 1000. Without being not limited to this, by providing a drive unit such as the air cylinder 101 to vertically drive each of the lift pins 14 for enabling each of the lift pins to move up and down each lift pin 14 or a drive unit such as the air cylinder 101 to vertically drive every specified number of lift pins 14 for enabling each of the lift pins to move up and down every specified number of lift pins 14 and successively moving the plurality of lift pins 14 one by one or every specified number of pins, the substrate may be simply made removable from the substrate electrode 6 or the adhesive sheet 13.

[0130] Next, the drive ring 100 is moved down by driving the air cylinder 101 under the operation control of the control unit 1000 to simultaneously gradually move down the plurality of lift pins 14, firstly bringing the neighborhood of the center of the substrate 9 in contact with the adhesive sheet 13 provided on the surface of the substrate electrode 6 (FIG. 2B).

[0131] By further moving down the lift pins 14, the peripheral portion of the substrate 9 are also brought in contact with the adhesive sheet 13, allowing almost the entire one surface of the substrate 9 to be brought in contact with the adhesive sheet 13 provided on the surface of the substrate electrode 6 (FIG. 2C).

[0132] By using the above-mentioned transportation procedure, it is feasible to prevent the occurrence of a gap, in which gas remains, between the substrate 9 and the adhesive sheet 13.

[0133] The substrate 9 was placed on the substrate electrode 6, and thereafter, a silicon oxide film on the substrate 9 was subjected to an etching process on the condition that the vacuum vessel 1 is supplied with CF₄ gas at a rate of 5 sccm and Ar gas at a rate of 45 sccm with the temperature of the substrate electrode 6 maintained at 30° C. and high-frequency power was applied by 500 W to the coil 8 and 200 W to the substrate electrode 6 with the internal pressure of the vacuum vessel 1 maintained at 3 Pa. Consequently, the etching was able to be carried out at an etching rate of 100 nm/min. The processing time was 200 seconds including an over-etching time. As a result, the burning of the photoresist did not occur, and satisfactory etching process was able to be carried out. When the temperature of the substrate 9 was measured on same conditions, the temperature of the substrate 9 immediately before the end of the etching was 57° C. For the sake of comparison, the etching process was carried out on similar conditions by the conventional system (construction having no adhesive sheet). Consequently, the burning of the photoresist occurred, and the etching failed. Moreover, when the temperature of the substrate 9 was measured on same conditions, the temperature of the substrate 9 immediately before the end of the etching was 195° C.

[0134] As described above, the reason why the temperature of the substrate 9 was significantly lowered in comparison with the prior-art example was that the processing was able to be carried out while effecting heat exchange between the substrate 9 and the substrate electrode 6 via the adhesive sheet 13.

[0135] When detaching the substrate 9 from the adhesive sheet 13 after the processing, reversely to the aforementioned transportation procedure, there is a procedure for firstly moving up the drive ring 100 by means of the air cylinder 101 under the operation control of the control unit 1000 to simultaneously gradually move up the plurality of lift pins 14, detaching the substrate 9 from the adhesive sheet 13 in a peeling-off manner and thereafter transporting the substrate 9 to the transportation arm 23 to unload the substrate 9 from inside the vacuum vessel 1.

[0136] At this time, if the substrate 9 is supported aslant with respect to the surface of the adhesive sheet 13 by means of long lift pins 14 and short lift pins 14 instead of simultaneously detaching the substrate 9 from the adhesive sheet 13 by, for example, making the plurality of lift pins 14 have different lengths, then the substrate 9 may be more smoothly detached from the surface of the adhesive sheet 13 by firstly detaching some portions in the periphery of the substrate 9 from the surface of the adhesive sheet 13 by means of the long lift pins 14 and thereafter detaching the remaining portions in the periphery of the substrate 9 from the surface of the adhesive sheet 13 by means of the short lift pins 14 instead of simultaneously detaching the periphery of the substrate 9 from the surface of the adhesive sheet 13. In order to perform the above operation, the lift pins 14 may be moved up separately as described hereinabove.

[0137]FIGS. 3A through 3C show another example of the processes for placing the substrate 9 on the substrate electrode 6. First of all, the substrate 9 is transported into the vacuum vessel 1, and thereafter, the substrate 9 is held (FIG. 3A). At this time, the lift pins 14, which move up and down in the through holes 6 a provided for a substrate electrode 6A having a convex portion 6 b that protrudes while being curved upward so that the center portion becomes the top, are provided in the vicinity of the outer peripheral portion of the substrate electrode 6A. Therefore, the substrate 9 is deformed in a convex shape protruding toward the substrate electrode 6A.

[0138] Next, the lift pins 14 are gradually moved down to bring the neighborhood of the center of the substrate 9 in contact with the adhesive sheet 13 provided on the surface of the convex portion 6 b of the convex substrate electrode 6A that has the surface of the convex portion 6 b of which the center portion in the lateral direction of the figure is curved and protruded (FIG. 3B). Further, by moving down the lift pins 14, almost the entire one surface of the substrate 9 can be brought in contact with the adhesive sheet 13 provided on the surface of the convex portion 6 b of the substrate electrode 6A (FIG. 3C). In this example, the convex substrate electrode 6A having a curvature of, for example, {fraction (1/100)} to {fraction (1/10)} is employed. Therefore, when handling a substrate 9 that is less prone to deformation, the substrate 9 can reliably be brought in contact with the adhesive sheet 13 initiatively from the neighborhood of the center of substrate 9, and the possibility of the occurrence of a gap between the substrate 9 and the adhesive sheet 13 can be reduced. The gap reducing effect is a little when the curvature is smaller than {fraction (1/100)}, while the circuit pattern formed on the substrate 9 tends to easily suffer damage when the curvature exceeds {fraction (1/10)}. Therefore, the aforementioned range is preferable.

[0139]FIGS. 4A through 4C show yet another example of the processes for placing the substrate 9 on the substrate electrode 6. First of all, the substrate 9 is transported into the vacuum vessel 1, and thereafter, the substrate 9 is held (FIG. 4A). In this example, the substrate 9 is made of a material that is less prone to deformation, and therefore, the degree of deformation of the substrate 9 protruding toward the substrate electrode 6 is remarkably less than in the case of FIGS. 2A through 2C and FIGS. 3A through 3C.

[0140] Next, the lift pins 14 are moved down to bring the neighborhood of the center of the substrate 9 in contact with the adhesive sheet 13 provided on the surface of the convex substrate electrode 6 (FIG. 4B).

[0141] Next, by moving down a clamp ring 16 by means of ring elevation rods 15 to press the outer peripheral portion of the substrate 9 against the substrate electrode 6, almost the entire one surface of the substrate 9 can be brought in contact with the adhesive sheet 13 provided on the surface of the substrate electrode 6 (FIG. 4C). In this example, the convex substrate electrode 6 is employed. Therefore, even in handling a substrate 9 that is less prone to deformation, the substrate 9 can reliably be brought in contact with the adhesive sheet 13 initiatively from the neighborhood of the center of the substrate 9, and the possibility of the occurrence of a gap between the substrate 9 and the adhesive sheet 13 can be reduced.

[0142] A lower surface of the clamp ring 16 brought in contact with the substrate 9 may be partially provided with adhesive members 16 d as pressing assistance members as indicated by the dotted lines in FIG. 4A. With this arrangement, by generating adhesive forces between the ring and the substrate 9, the substrate 9 is more reliably pressed against the substrate electrode 6 without displacement when the substrate 9 is pressed against the substrate electrode 6 by the clamp ring 16, and by lifting the substrate 9 a little by the adhesive forces of the adhesive members 16 d when the clamp ring 16 is moved up, the substrate 9 may be easily detached from the substrate electrode 6. Also, by providing the clamp ring 16 partially or entirely with a corrugated member that has no adhesive force and has mere corrugation as another pressing assistance member in the portions indicated by the dotted lines in FIG. 4A of the clamp ring 16 and generating a frictional force between the ring 16 and the substrate 9 when the substrate 9 is pressed against the substrate electrode 6 by the clamp ring 16, the substrate 9 can be more reliably pressed against the substrate electrode 6 without displacement.

[0143] Moreover, as shown in FIGS. 24A and 24B, by disposing an adhesive sheet 13 with interposition of a gap 90 with respect to a recess portion 6 d formed on the surface of the substrate electrode 6 and pressing the adhesive sheet 13 together with the substrate 9 by means of the clamp ring 16, the adhesive sheet 13 may enter the gap 90, thereby preventing the formation of a gap of foams or the like between the substrate 9 and the substrate electrode 6. Furthermore, as shown in FIG. 24C, by contracting the adhesive sheet 13 itself without forming the recess portion 6 d on the surface of the substrate electrode 6 when the adhesive sheet 13 is pressed together with the substrate 9 by the clamp ring 16, a gap of foams or the like may be prevented from occurring between the substrate 9 and the substrate electrode 6.

[0144] (Second Embodiment)

[0145] A second embodiment of the present invention will be described with reference to FIGS. 5 through 17C.

[0146]FIG. 5 shows a sectional view of a plasma processing apparatus used in the second embodiment of the present invention.

[0147] Referring to FIG. 5, by evacuating a vacuum vessel 1 by a turbo-molecular pump 3 as an exhauster while introducing a specified gas from a gas supply unit 2 into the vacuum vessel 1 and by applying high-frequency power of 13.56 MHz to a coil 8 provided along a dielectric plate 7 opposite to a substrate electrode 6 by a coil use high-frequency power supply 5 while maintaining the interior of the vacuum vessel 1 to a specified pressure by a pressure-regulating valve 4, then inductive-coupling type plasma is generated in the vacuum vessel 1, and a substrate 9 placed on the substrate electrode 6 can be subjected to plasma processing.

[0148] Moreover, a substrate electrode use high-frequency power supply 10 for supplying high-frequency power to the substrate electrode 6 is provided, allowing the ion energy that reaches the substrate 9 to be controlled. The turbo-molecular pump 3 and the exhaust port 11 are disposed just under the substrate electrode 6, and the pressure-regulating valve 4 is an up-and-down valve disposed just under the substrate electrode 6 and just over the turbo-molecular pump 3. The substrate electrode 6 is fixed to the vacuum vessel 1 with four props 12.

[0149] The substrate 9 is placed on a tray 17, and an adhesive sheet 13 is provided between the tray 17 and a substrate 9, making it possible to carry out the processing while effecting heat exchange between the substrate 9 and the tray 17 via the adhesive sheet 13. A silicone rubber film is used as the adhesive sheet 13. This adhesive sheet 13 has a thermal conductivity of 0.2 W/m·K, Asker C of 60, hardness of 55, and a thickness of 0.2 mm.

[0150] The tray 17 is preferably made of a material, which has a thickness of 2 to 5 mm, hydrochloric acid resistance and good thermal conductivity and on the surface of which an oxide film is formed. The tray is preferably made of aluminum whose surface is processed with alumite as an oxide film.

[0151] A recess portion 17 a for accommodating the adhesive sheet 13 provided in the tray 17 may have roughly same size as that of the adhesive sheet 13 or made greater than the adhesive sheet 13 as described hereinabove as shown in FIGS. 24A and 24B, so that the adhesive sheet 13 can protrude radially outwardly when the substrate 9 is pressed by the clamp ring 16.

[0152] The substrate 9 and the tray 17 were placed on the substrate electrode 6, and thereafter, a silicon oxide film on the substrate 9 was subjected to an etching process on the condition that the vacuum vessel 1 is supplied with CF₄ gas at a rate of 5 sccm and Ar gas at a rate of 45 sccm with the temperature of the substrate electrode 6 maintained at 30° C. and high-frequency power was applied by 500 W to the coil 8 and 200 W to the substrate electrode 6 with the internal pressure of the vacuum vessel 1 maintained at 3 Pa. Consequently, the etching was able to be carried out at an etching rate of 100 nm/min.

[0153] The processing time was 200 seconds including an over-etching time. As a result, the burning of the photoresist did not occur, and satisfactory etching process was able to be carried out. When the temperature of the substrate 9 was measured on the same conditions, the temperature of the substrate 9 immediately before the end of the etching was 92° C. For the sake of comparison, the etching process was carried out on similar conditions by the conventional system (construction having no adhesive sheet). Consequently, the burning of the photoresist occurred, and the etching failed. Moreover, when the temperature of the substrate 9 was measured on the same conditions, the temperature of the substrate 9 immediately before the end of the etching was 200° C.

[0154] As described above, the reason why the temperature of the substrate 9 was significantly lowered in comparison with the prior-art example is that the processing is able to be carried out while effecting heat exchange between the substrate 9 and the tray 17 via the adhesive sheet 13. That is, it can be considered that the temperature rise due to plasma exposure is reduced since the thermal capacity of the tray 17 is much larger (ten times or more) than the thermal capacity of only the substrate 9. When the tray 17 is used, the temperature of the substrate 9 is disadvantageously made higher than the construction of the first embodiment of the present invention using no tray 17. However, by using the tray 17, the possibility of the occurrence of positional shift when the substrate 9 is transported in a vacuum is remarkably reduced. That is, the substrate positional shift might be easily caused with respect to the transportation arm during transportation of only the thin light substrate 9. However, by using the tray 17 that has considerable weight and thickness, the substrate positional shift is less likely to occur with respect to the transportation arm during transportation, and this produces an effect of facilitating the transportation in a vacuum.

[0155] As shown in FIG. 6, by providing an adhesive sheet 18 between the substrate electrode 6 and the tray 17 and carrying out the processing while effecting heat exchange between the substrate electrode 6 and the tray 17 via the adhesive sheet 18, the temperature rise of the substrate 9 can further be suppressed. Regarding such a construction, FIGS. 7A and 7B show processes for placing on the substrate electrode 6 the tray 17 on which the substrate 9 is placed. First of all, the tray 17 on which the substrate 9 is placed is transported into the vacuum vessel 1, and thereafter, the tray 17 is held (FIG. 7A).

[0156] Next, the lift pins 14 are gradually moved down to bring almost the entire one surface of the tray 17 in contact with the adhesive sheet 18 provided on the surface of the substrate electrode 6 (FIG. 7B). If the flatness and parallelism of the tray 17 and the substrate electrode 6 are sufficient, then it is feasible to prevent the occurrence of a gap between the tray 17 and the adhesive sheet 18.

[0157]FIGS. 8A through 8C show another example of the processes for placing the tray 17 on the substrate electrode 6. First of all, the tray 17 on which the substrate 9 is placed is transported into the vacuum vessel 1, and thereafter, the tray 17 is held (FIG. 8A).

[0158] Next, the lift pins 14 are moved down to bring the tray 17 in contact with the adhesive sheet 18 provided on the surface of the substrate electrode 6 (FIG. 8B).

[0159] Next, by moving down the clamp ring 16 by means of the ring elevation rods 15 and pressing the outer peripheral portion of the tray 17 against the substrate electrode 6, almost the entire one surface of the tray 17 can be brought in contact with the adhesive sheet 18 provided on the surface of the substrate electrode 6 (FIG. 8C). In this example, it is feasible to more reliably prevent the occurrence of a gap between the tray 17 and the adhesive sheet 18.

[0160] It is also acceptable to press the outer peripheral portion of the substrate 9 against the substrate electrode 6 instead of pressing the outer peripheral portion of the tray 17 against the substrate electrode 6. When the substrate 9 is susceptible to a force perpendicular to its surface, it is preferable to press the outer peripheral portion of the tray 17 against the substrate electrode 6 in terms of less damage inflicted on the substrate 9.

[0161] The substrate 9 is transported and placed on the adhesive sheet 13 in the aforementioned embodiments. However, as shown in FIGS. 25A through 25C, it is acceptable to transport the substrate 9 and the adhesive sheet 13 in an integrated body, place the same on a plurality of lift pins 14, place the resulting body on the substrate electrode 6 and adhesively fix the same in a state in which the adhesive sheet 13 is preparatorily detachably stuck tightly to the lower surface of the substrate 9 and no foams exist. When the substrate 9 is moved up and down, the plurality of lift pins 14 directly support the substrate 9 penetrating the adhesive sheet 13, the substrate 9 is allowed to be stably moved up and down. As described above, if the substrate 9 is transported with the adhesive sheet 13 preparatorily stuck to the lower surface of the substrate 9, it is feasible to effectively prevent the occurrence of a gap as a consequence of the intrusion of foams between the lower surface of the substrate 9 and the adhesive sheet 13 when the substrate 9 is placed on the substrate electrode 6.

[0162] Moreover, as shown in FIG. 26, the adhesive sheet 13 is not limited to the one constructed only of one layer but allowed to be constructed of two layers. That is, as shown in FIG. 26, the adhesive sheet 13 may be constructed of two layers of an upper adhesive sheet 13 a and a lower adhesive sheet 13 b. In this case, when (hardness of upper adhesive sheet 13 a>hardness of lower adhesive sheet 13 b), the upper adhesive sheet 13 a has lower adhesion and abundant detachability. Therefore, this construction is appropriate for the adhesive sheet attached to the upper surface of the electrode or the tray. Conversely, when (hardness of upper adhesive sheet 13 a<hardness of lower adhesive sheet 13 b), the lower adhesive sheet 13 b has lower adhesion and abundant detachability. Therefore, this construction is appropriate for the adhesive sheet attached to the lower surface of the tray or the substrate 9.

[0163]FIG. 9 is a plan view showing the overall construction of the plasma processing apparatus used in the second embodiment of the present invention. The apparatus is constructed of three units of a reaction chamber 19 (including the vacuum vessel 1) for carrying out plasma processing, a load lock chamber 20, and an atmospheric transporting section 21, and the units are partitioned by gate valves 22 that are opening-and-closing gates. The load lock chamber 20 is internally provided with the transportation arm 23 and is able to carry out reception and delivery of the tray 17 between the atmospheric transporting section 21 and the load lock chamber 20 and reception and delivery of the tray 17 between the reaction chamber 19 and the load lock chamber 20. An atmospheric arm 24 is to receive and deliver the substrate 9 or the tray 17 between the arm and a substrate cassette 25 or a tray cassette 26.

[0164] The atmospheric arm 24 performs the reception and delivery of the substrate 9 or the tray 17 between the arm 24 and the substrate placement station 27 for placing the substrate 9 on the tray 17 on the surface of which the adhesive sheet 13 is provided. The substrate cassette 25 and the tray cassette 26 are provided on a cassette elevation table 28. When the atmospheric arm 24 receives and delivers the substrate cassette 25 or the tray cassette 26 and the substrate 9 or the tray 17, the atmospheric arm 24 carries out a back-and-forth motion as shown in FIG. 10, while the cassette elevation table 28 moves up and down in accordance with appropriate timing.

[0165]FIGS. 11A through 11E show a procedure for sticking the adhesive sheet 13 to the tray 17. First of all, the tray 17 and the adhesive sheet 13 whose both surfaces are covered with protection films 29 and 30 are prepared (FIG. 11A).

[0166] Next, part of the protection film 30 is peeled off and brought in contact with the bottom surface of an adhesive sheet-disposing recess portion 17 a of the tray 17, and a roller 31 is subsequently rotated on the protection film 29 while tensioning one end of the protection film 30, thus sticking the adhesive sheet 13 to the inside of the adhesive sheet-disposing recess portion 17 a of the tray 17 (FIGS. 11B and 11C).

[0167] Next, the protection film 29 is peeled off (FIG. 11D).

[0168] The tray 17, which is provided with the adhesive sheet 13 on its surface on which the substrate 9 is to be placed, can be obtained according to the aforementioned procedure (FIG. 11E).

[0169] In order to improve the adhesion between the substrate 9 and the tray 17 in the process for placing the substrate 9 on the tray 17, it is sometimes preferable that a tray 17A has a convex shape having a surface of a convex portion 17 b whose center portion in the lateral direction in the figure is curved and protruded. FIGS. 12A through 12E show a procedure for sticking the adhesive sheet 13 to the tray 17A in the above case. First of all, the convex tray 17A and the adhesive sheet 13 whose both surfaces are covered with protection films 29 and 30 are prepared (FIG. 12A).

[0170] Next, part of the protection film 30 is peeled off and brought in contact with the tray 17A, and a roller 31 is subsequently rotated on the protection film 29 while tensioning one end of the protection film 30, thus sticking the adhesive sheet 13 to the tray 17A (FIGS. 12B and 12C).

[0171] Next, the protection film 29 is peeled off (FIG. 12D). The convex tray 17A, which is provided with the adhesive sheet 13 on its surface on which the substrate 9 is to be placed, can be obtained according to the aforementioned procedure (FIG. 12E).

[0172] As shown in FIG. 27, it is acceptable to place the substrate 9 on the adhesive sheet 13 of the tray 17A and rotate the roller 131 on the substrate 9 for the removal of the gap between the substrate 9 and the adhesive sheet 13.

[0173]FIG. 13 and FIGS. 14A through 14C show another example of the processes for placing the substrate 9 on the tray 17.

[0174]FIG. 13 is a perspective view of the tray 17, in which through holes 32 for moving up and down the lift pins 33 are provided at, for example, the bottom surface of the adhesive sheet-disposing recess portion 17 a. First of all, the tray 17 and the substrate 9 are transported onto the substrate placement station 27 (see FIG. 9), and thereafter, the substrate 9 is held above the tray 17 (FIG. 14A). At this time, the lift pins 33 that move up and down inside the through holes 32 provided at the tray 17 are disposed in the vicinity of the outer peripheral portion of the tray 17. Therefore, the substrate 9 is deformed in a convex shape protruding toward the tray 17. Next, the lift pins 33 are gradually moved down, and the neighborhood of the center of the substrate 9 is brought in contact with the adhesive sheet 13 provided on the surface of the tray 17 (FIG. 14B).

[0175] By further moving down the lift pins 33, almost the entire one surface of the substrate 9 can be brought in contact with the adhesive sheet 13 provided on the surface of the tray 17 (FIG. 14C).

[0176] By using the aforementioned procedure, it is feasible to prevent the occurrence of a gap between the substrate 9 and the adhesive sheet 13 (in other words, no foams enter).

[0177]FIGS. 15A through 15C show another example of the processes for placing the substrate 9 on the tray 17A. First of all, the tray 17A and the substrate 9 are transported onto the substrate placement station 27 (see FIG. 9), and thereafter, the substrate 9 is held above the tray 17A (FIG. 15A). At this time, the lift pins 33, which move up and down in the through holes 32 provided at the tray 17A, are disposed in the vicinity of the outer peripheral portion of the tray 17A. Therefore, the substrate 9 is deformed in a convex shape protruding toward the tray 17A.

[0178] Next, the lift pins 33 are gradually moved down, and the neighborhood of the center of the substrate 9 is brought in contact with the adhesive sheet 13 provided on the surface of the tray 17A (FIG. 15B).

[0179] By further moving down the lift pins 33, almost the entire one surface of the substrate 9 can be brought in contact with the adhesive sheet 13 provided on the surface of the tray 17A (FIG. 15C). In this example, since the convex tray 17A is employed, even in handling a substrate 9 that is less prone to deformation, the substrate can reliably be brought in contact with the adhesive sheet 13 initiatively from the neighborhood of the center of the substrate 9, and the possibility of the occurrence of a gap between the substrate 9 and the adhesive sheet 13 can be reduced.

[0180]FIGS. 16A through 16C show yet another example of the processes for placing the substrate 9 on the tray 17A. The tray 17A and the substrate 9 are transported onto the substrate placement station 27 (see FIG. 9), and thereafter, the substrate 9 is held above the tray 17A (FIG. 16A). In this example, the substrate 9 is made of a material that is less prone to deformation, and therefore, the degree of deformation of the substrate 9 protruding toward the tray 17A is remarkably less than in the case of FIGS. 14A through 14C and FIGS. 15A through 15C.

[0181] Next, the lift pins 33 are moved down, and the neighborhood of the center of the substrate 9 is brought in contact with the adhesive sheet 13 provided on the surface of the convex tray 17A (FIG. 16B).

[0182] Next, by moving down a frame-shaped or rod-shaped clamping jig 35 capable of contacting the outer peripheral portion of the substrate 9 with use of a plurality of jig elevation bars 34 and then pressing the outer peripheral portion of the substrate 9 against the tray 17A, almost the entire one surface of the substrate 9 can be brought in contact with the adhesive sheet 13 provided on the surface of the tray 17A (FIG. 16C).

[0183] In this example, since the convex tray 17A is employed, even in handling a substrate 9 that is less prone to deformation, the substrate 9 can reliably be brought in contact with the adhesive sheet 13 initiatively from the neighborhood of the center of substrate 9, and the possibility of the occurrence of a gap between the substrate 9 and the adhesive sheet 13 can be reduced. When transporting the tray 17A into the vacuum vessel 1, it is preferable to transport the tray 17A with the outer peripheral portion of the substrate 9 kept pressed against the tray 17A by the clamping jig 35.

[0184]FIGS. 17A through 17C show yet another example of the processes for placing the substrate 9 on the tray 17. First of all, the tray 17 and the substrate 9 are transported onto the substrate placement station 27 (see FIG. 9), and thereafter, the substrate 9 is held above the tray 17 (FIG. 17A). In this example, numbers of exhaust holes 36 are provided at the tray 17. Then, the lift pins 33 are moved down while exhausting the gas between the substrate 9 and the tray 17 by an exhausting unit 150, and the neighborhood of the center of the substrate 9 is brought in contact with the adhesive sheet 13 provided on the surface of the tray 17 (FIG. 17B).

[0185] By further moving down the lift pins 33, almost the entire one surface of the substrate 9 can be brought in contact with the adhesive sheet 13 provided on the surface of the tray 17 (FIG. 17C). In this example, the contact processes are carried out while exhausting the gas between the substrate 9 and the tray 17, and therefore, the possibility of the occurrence of a gap between the substrate 9 and the adhesive sheet 13 is low, and there is an advantage that foams are less likely to occur between the substrate 9 and the adhesive sheet 13.

[0186] It is noted that the substrate placement station 27 (see FIG. 9) may also be provided within a second vacuum vessel. In this case also, there is an advantage that foams are less likely to intervene between the substrate 9 and the adhesive sheet 13.

[0187] It is also possible that exhaust holes 36 are provided only at a central portion of the tray 17, as shown in FIG. 28, so that the substrate 9 is sucked at only its central portion to the adhesive sheet 13 so as to be affixable thereto sequentially from the central to the peripheral portion of the substrate 9, thus making it implementable to eliminate gaps or foams more effectively.

[0188] The foregoing embodiments of the present invention have been described only by way of example to illustrate some of many variations as to the configuration of the vacuum vessel (chamber), the system and arrangement of the plasma source, and the like within the application range of the present invention. It is needless to say that many other variations besides those illustrated above are conceivable for application of the present invention.

[0189] Although the foregoing embodiments have been described exemplarily on a case where the present invention is applied to dry etching, the present invention is of course applicable to CVD, sputtering, or other plasma processing.

[0190] Further, the foregoing embodiments have been described exemplarily on a case where the internal pressure of the vacuum vessel is 3 Pa. However, since it is over pressure ranges generally 500 Pa or lower that the heat exchange between a substrate and a substrate electrode, between a substrate and a tray, or between a tray and a substrate electrode matters in the prior art example, the present invention is particularly effective for such pressure ranges.

[0191] Further, although the foregoing embodiments have been described exemplarily on a case where a film on the substrate placed on the tray is processed, the present invention is applicable also to cases where the substrate itself is processed.

[0192] Further, although the foregoing embodiments have been described exemplarily on a case where an adhesive sheet is provided on one side of the tray, it is also possible that adhesive sheets are provided on both sides of the tray as shown in FIG. 18. In this case, there is no need for providing any adhesive sheet on the surface of the substrate electrode, thus making it easier to replace the adhesive sheets, advantageously.

[0193] Further, the foregoing embodiments have been described exemplarily on a case where the thermal conductivity of the adhesive sheet is 0.2 W/m·K. However, for enhancement of the heat exchange between a substrate and a substrate electrode, between a substrate and a tray or between a tray and a substrate electrode, the thermal conductivity of the adhesive sheet is preferably not less than 0.1 W/m·K.

[0194] Further, the foregoing embodiments have been described exemplarily on a case where the ASKER C of the adhesive sheet is 60. However, for enhancement of the heat exchange between a substrate and a substrate electrode, between a substrate and a tray, or between a tray and a substrate electrode, the ASKER C of the adhesive sheet is preferably not more than 80. With the ASKER C larger than 80, the adhesiveness would become poorer, causing the heat exchangeability to lower.

[0195] Further, the foregoing embodiments have been described exemplarily on a case where the hardness of the adhesive sheet is 55. However, for enhancement of the heat exchange between a substrate and a substrate electrode, between a substrate and a tray, or between a tray and a substrate electrode, the hardness of the adhesive sheet is preferably 50 to 60. With the hardness of the adhesive sheet lower than 50, the adhesive sheet would be too soft, allowing foams to easily enter into the adhesion surface. Conversely, with the hardness of the adhesive sheet higher than 60, the adhesive sheet would be too hard, resulting in poorer adhesiveness.

[0196] Further, the foregoing embodiments have been described exemplarily on a case where the thickness of the adhesive sheet is 0.2 mm. However, for enhancement of the heat exchange between a substrate and a substrate electrode, between a substrate and a tray, or between a tray and a substrate electrode, the thickness of the adhesive sheet is preferably 0.05 to 0.5 mm. With the thickness of the adhesive sheet smaller than 0.05 mm, the adhesive sheet would be less easy to handle, making it difficult to carry out the step of affixing the adhesive sheet to the substrate electrode or the tray, while the adhesive sheet itself would be insufficient in cushioning property, making it difficult to obtain flatness, with the result of deteriorated cooling efficiency. Conversely, with the thickness of the adhesive sheet larger than 0.5 mm, the thermal resistance would be become larger, causing the heat exchangeability to lower.

[0197] Further, although the foregoing embodiments have been described exemplarily on a case where the substrate is made of polyimide resin, the present invention is applicable to cases where various substrates are used. With an electrically conductive substrate used, there is a possibility that the temperature of the substrate can be controlled to some extent by electrostatic suction. Therefore, the present invention is effective particularly when the substrate is a dielectric. Examples of such cases may include cases where the substrate is made of glass, ceramics, resin sheet, or the like.

[0198] Further, the foregoing embodiments have been described exemplarily on a case where the thickness of the substrate is 0.4 mm. However, the present invention is particularly effective when the thickness of the substrate is 0.001 to 1 mm, and further particularly effective when the thickness of the substrate is 0.001 to 0.5 mm. With the thickness of the substrate less than 0.001 mm, substrate conveyance becomes difficult to carry out. Conversely, with the thickness of the substrate more than 1 mm, the substrate is large in thermal capacity, so that temperature change of the substrate under processing becomes relatively small. With the high-frequency power small (e.g., about 100 W), even if the thickness of the substrate is 0.5 mm to 1 mm, the substrate is large in thermal capacity, so that temperature change of the substrate under processing becomes relatively small. Otherwise, with the use of a large-scale, thin and solid, crack-prone substrate (silicon, glass, ceramics etc.), especially when the substrate has a thickness of not more than 1 mm and an area of not less than 0.1 m², it is difficult to use gas as a heating medium as described in the prior art, and therefore the present invention is particularly effective.

[0199] Further, the foregoing embodiments have been described exemplarily on a case where the substrate has a thickness h of 0.0004 m, a Young's modulus E of 3 GPa, a Poisson's ratio ν of 0.3, and a circular shape having a diameter a of 0.15 m. However, the present invention is a plasma processing method which is effective particularly when 600×(1−ν²)a⁴/(256×Eh³)>0.005 (m), where E (Pa) is substrate's Young's modulus, ν is substrate's Poisson's ratio, a (m) is substrate's characteristic length, and h (m) is substrate's thickness. That is, the present invention produces particularly large effects when such substrates as those satisfying the above relational expression are processed.

[0200] Generally, given that a disc has a Young's modulus of E (Pa), a Poisson's ratio of ν, a diameter of a (m), and a thickness of h (m), a uniformly distributed load of p (Pa), when applied to the disc with the disc fixed at its periphery, results in a flexure amount of 3×(1−ν²)pa⁴/(256×Eh³) (m) at the center of the disc. As is known, generally, 200 Pa or higher gas pressure is necessary in order to fulfill the temperature control of the substrate by feeding gas serving as a heating medium to between the substrate and the substrate electrode with the substrate fixed at its periphery by a clamp ring.

[0201] Accordingly, the substrate satisfying the expression that 600×(1−ν²)a⁴/(256×Eh³)>0.005 means a substrate which has its periphery fixed and which would result in a flexure of 0.005 m (=5 mm) or more with application of a 200 Pa gas pressure. Occurrence of such large deformation might not only impair the uniformity of the processing but also cause occurrence of abnormal discharge in the space formed between the substrate and the substrate electrode, and besides might cause the device formed on the substrate to be broken by stress.

[0202] The above description has been made on a circular-shaped substrate. Otherwise, also for rectangular or other shapes, the range over which the present invention produces great application effects can be defined, in terms of their characteristic length a (e.g., diagonal line of a rectangular shape), approximately by the expression that 600×(1−ν²)a⁴/(256×Eh³)>0.005. Conversely, in the case of substrates which do not satisfy the above expression, those substrates are less liable to deformation even with the use of gas as a heating medium and therefore, in some cases, may be processed by conventional methods without the need for applying the present invention.

[0203] Another modification example of the above embodiment of the present invention is shown in FIGS. 31-33. In FIGS. 31-33, a plurality of resin tapes 130 are arranged on the surface of the substrate electrode 6 via specified gaps, and then an adhesive sheet 13C is arranged on the plurality of resin tapes 130 and the surface of the substrate electrode 6 to fix the adhesive sheet 13C onto the plurality of resin tapes 130 and the surface of the substrate electrode 6 with an adhesive force of the adhesive sheet 13C. In this state, approximately strip-shaped spaces 132 are formed between each resin tape 130 and the adhesive sheet 13C on the both sides of each resin tape 130, whereas onto the upper surface of the adhesive sheet 13C, an uneven shape defined by the plurality of resin tapes 130 is transferred via the adhesive sheet 13C itself, while the difference level of the uneven shape defined by the plurality of resin tapes 130 is reduced slightly, resulting in obtaining an uneven upper surface at the adhesive sheet 13C.

[0204] As shown in FIG. 33, both ends of each resin tape 130 are projected outside of an area where the adhesive sheet 13C is located, and thus, both ends of the approximately strip-shaped spaces 132 defined between each resin tape 130 and the adhesive sheet 13C are opened to the circumference of the adhesive sheet 13C, without being closed by the adhesive sheet 13C. As a result, in sticking the adhesive sheet 13C to the substrate electrode 6, air in the approximately strip-shaped spaces 132 on the substrate electrode side is discharged through the approximately strip-shaped spaces 132 when the inside of the vacuum vessel is evacuated, resulting in prevention of any deformation of the adhesive sheet 13C due to expansion of foams.

[0205] When a substrate 9 is placed on the uneven upper surface of the adhesive sheet 13C to fix the substrate 9 to the adhesive sheet 13C with the adhesive force of the adhesive sheet 13C, approximately strip-shaped spaces 131 are defined by the uneven upper surface of the adhesive sheet 13C and the lower surface of the substrate 9 while both ends of the spaces 131 are opened in their longitudinal directions. Therefore, when the substrate 9 is placed on the adhesive sheet 13C, air in the approximately strip-shaped spaces 131 is discharged through the approximately strip-shaped spaces 131 when the inside of the vacuum vessel is evacuated, resulting in prevention of any deformation of the adhesive sheet 13C due to expansion of foams.

[0206] In order to form such an uneven surface at the upper surface of the adhesive sheet 13C, instead of provision of the plural resin tapes 130 described above, grooves may be formed at the surface of the substrate electrode 6 itself. The above means for preventing expansion of foams can be applied to portions between the tray and the substrate, or portions between the substrate electrode and the tray.

[0207] As apparent from the foregoing description, according to the plasma processing method of the first aspect of the present invention, there is provided a plasma processing method which comprises: evacuating inside of a vacuum chamber and supplying gas into the vacuum chamber and the generating plasma in the vacuum chamber while controlling interior of the vacuum chamber to a specified pressure; and processing a substrate or a film on a substrate placed on a substrate electrode in the vacuum chamber while carrying out heat exchange between the substrate and the substrate electrode via an adhesive sheet disposed between the substrate electrode and the substrate. Therefore, the temperature controllability of the substrate can be improved.

[0208] Also, according to the plasma processing method of the second aspect of the present invention, there is provided a plasma processing method which comprises: evacuating inside of a vacuum chamber and supplying gas into the vacuum chamber and then generating plasma in the vacuum chamber while controlling interior of the vacuum chamber to a specified pressure; and processing a substrate or a film on a substrate on a tray placed on a substrate electrode in the vacuum chamber while carrying out heat exchange between the tray and the substrate electrode via an adhesive sheet disposed between the tray and the substrate. Therefore, the temperature controllability of the substrate can be improved.

[0209] Also, according to the plasma processing method of the fourth aspect of the present invention, there is provided a plasma processing method which comprises: transporting a substrate into a vacuum chamber; holding the substrate while deforming the substrate in a convex shape toward a substrate electrode in the vacuum chamber; bringing a neighborhood of a center portion of the substrate deformed in the convex shape in contact with an adhesive sheet provided on a surface of the substrate electrode; bringing almost an entire one surface of the substrate in contact with the adhesive sheet provided on the surface of the substrate electrode; and processing the substrate or a film on the substrate by evacuating inside of the vacuum chamber and supplying gas into the vacuum chamber and then generating plasma in the vacuum chamber while controlling interior of the vacuum chamber to a specified pressure. Therefore, the temperature controllability of the substrate can be improved.

[0210] Also, according to the plasma processing method of the fifth aspect of the present invention, there is provided a plasma processing method which comprises: transporting a substrate into a vacuum chamber; holding the substrate above a convex substrate electrode in the vacuum chamber; bringing a neighborhood of a center portion of the substrate in contact with an adhesive sheet provided on a surface of the substrate electrode; bringing almost an entire one surface of the substrate in contact with the adhesive sheet provided on the surface of the substrate electrode by pressing an outer edge portion of the substrate against the substrate electrode; and processing the substrate or a film on the substrate by evacuating inside of the vacuum chamber and supplying gas into the vacuum chamber and then generating plasma in the vacuum chamber while controlling interior of the vacuum chamber to a specified pressure. Therefore, the temperature controllability of the substrate can be improved.

[0211] Also, according to the plasma processing method of the sixth aspect of the present invention, there is provided a plasma processing method which comprises: bringing almost and entire one surface of a substrate in contact with an adhesive sheet provided on a surface of a tray; transporting the tray into a vacuum chamber; holding the tray above a substrate electrode in the vacuum chamber; placing the tray on the substrate electrode; and processing the substrate or a film on the substrate by evacuating inside of the vacuum chamber and supplying gas into the vacuum chamber and then generating plasma in the vacuum chamber while controlling interior of the vacuum chamber to a specified pressure. Therefore, the temperature controllability of the substrate can be improved.

[0212] Also, according to the plasma processing apparatus of the 16th aspect of the present invention, there is provided a plasma processing apparatus which comprises: a vacuum chamber; a gas supply unit for supplying gas into the vacuum chamber; an exhausting unit for exhausting interior of the vacuum chamber; a pressure-regulating valve for controlling the interior of the vacuum chamber to a specified pressure; a substrate electrode for placing thereon a substrate in the vacuum chamber; a high-frequency power supply capable of supplying a high-frequency power to the substrate electrode or a plasma source; and an adhesive sheet, which is disposed on a surface of the substrate electrode and on which the substrate is placed. Therefore, the temperature controllability of the substrate can be improved.

[0213] Also, according to the plasma processing apparatus of the 17th aspect of the present invention, there is provided a plasma processing apparatus which comprises: a substrate mounting station for placing a substrate on a tray having a surface provided with an adhesive sheet; a vacuum chamber; a gas supply unit for supplying gas into the vacuum chamber; an exhausting unit for exhausting interior of the vacuum chamber; a pressure-regulating valve for controlling the interior of the vacuum chamber to a specified pressure; a substrate electrode for placing thereon the tray in the vacuum chamber; and a high-frequency power supply capable of supplying a high-frequency power to the substrate electrode or a plasma source. Therefore, the temperature controllability of the substrate can be improved.

[0214] Also, according to the tray for plasma processing of the 22nd aspect of the present invention, there is provided a tray for plasma processing which comprises: an adhesive sheet disposed on a surface on which the substrate is placed. Therefore, the temperature controllability of the substrate can be improved.

[0215] In addition, combining any arbitrary embodiments together appropriately from among the foregoing various embodiments allows their respective effects to be produced.

[0216] Although the present invention has been fully described in connection with the preferred embodiments thereof with reference to the accompanying drawings, it is to be noted that various changes and modifications are apparent to those skilled in the art. Such changes and modifications are to be understood as included within the scope of the present invention as defined by the appended claims unless they depart therefrom. 

What is claimed is:
 1. A plasma processing method comprising: evacuating inside of a vacuum chamber and supplying gas into the vacuum chamber and the generating plasma in the vacuum chamber while controlling interior of the vacuum chamber to a specified pressure; and processing a substrate or a film on a substrate placed on a substrate electrode in the vacuum chamber while carrying out heat exchange between the substrate and the substrate electrode via an adhesive sheet disposed between the substrate electrode and the substrate.
 2. A plasma processing method comprising: evacuating inside of a vacuum chamber and supplying gas into the vacuum chamber and then generating plasma in the vacuum chamber while controlling interior of the vacuum chamber to a specified pressure; and processing a substrate or a film on a substrate on a tray placed on a substrate electrode in the vacuum chamber while carrying out heat exchange between the tray and the substrate via an adhesive sheet disposed between the tray and the substrate.
 3. The plasma processing method as claimed in claim 2, wherein the substrate or the film on the substrate is processed while carrying out heat exchange between the substrate electrode and the tray via the adhesive sheet disposed between the substrate electrode and the tray.
 4. A plasma processing method comprising: transporting a substrate into a vacuum chamber; holding the substrate while deforming the substrate in a convex shape toward a substrate electrode in the vacuum chamber; bringing a neighborhood of a center portion of the substrate deformed in the convex shape in contact with an adhesive sheet provided on a surface of the substrate electrode; bringing almost an entire one surface of the substrate in contact with the adhesive sheet provided on the surface of the substrate electrode; and processing the substrate or a film on the substrate by evacuating inside of the vacuum chamber and supplying gas into the vacuum chamber and then generating plasma in the vacuum chamber while controlling interior of the vacuum chamber to a specified pressure.
 5. A plasma processing method comprising: transporting a substrate into a vacuum chamber; holding the substrate above a convex substrate electrode in the vacuum chamber; bringing a neighborhood of a center portion of the substrate in contact with an adhesive sheet provided on a surface of the substrate electrode; bringing almost an entire one surface of the substrate in contact with the adhesive sheet provided on the surface of the substrate electrode by pressing an outer edge portion of the substrate against the substrate electrode; and processing the substrate or a film on the substrate by evacuating inside of the vacuum chamber and supplying gas into the vacuum chamber and then generating plasma in the vacuum chamber while controlling interior of the vacuum chamber to a specified pressure.
 6. A plasma processing method comprising: bringing almost and entire one surface of a substrate in contact with an adhesive sheet provided on a surface of a tray; transporting the tray into a vacuum chamber; holding the tray above a substrate electrode in the vacuum chamber; placing the tray on the substrate electrode; and processing the substrate or a film on the substrate by evacuating inside of the vacuum chamber and supplying gas into the vacuum chamber and then generating plasma in the vacuum chamber while controlling interior of the vacuum chamber to a specified pressure.
 7. The plasma processing method as claimed in claim 1, wherein the adhesive sheet has a thermal conductivity of not smaller than 0.1 W/m·K.
 8. The plasma processing method as claimed in claim 1, wherein the adhesive sheet has Asker C of not greater than
 80. 9. The plasma processing method as claimed in claim 1, wherein the adhesive sheet has a hardness of 50 to
 60. 10. The plasma processing method as claimed in claim 1, wherein the adhesive sheet has a thickness of 0.05 to 0.5 mm.
 11. The plasma processing method as claimed in claim 1, wherein the substrate is made of glass or ceramics.
 12. The plasma processing method as claimed in claim 1, wherein the substrate is a resin sheet.
 13. The plasma processing method as claimed in claim 1, wherein the substrate has a thickness of 0.001 to 1 mm.
 14. The plasma processing method as claimed in claim 1, wherein the substrate has a thickness of 0.001 to 0.5 mm.
 15. The plasma processing method as claimed in claim 1, wherein, assuming that the substrate has a Young's modulus E (Pa), the substrate has a Poisson's ratio ν, the substrate has a characteristic length a (m) and the substrate has a thickness h (m), then there holds an expression: 600×(1−ν²)a⁴/(256×Eh³)>0.005 (m).
 16. A plasma processing apparatus comprising: a vacuum chamber; a gas supply unit for supplying gas into the vacuum chamber; an exhausting unit for exhausting interior of the vacuum chamber; a pressure-regulating valve for controlling the interior of the vacuum chamber to a specified pressure; a substrate electrode for placing thereon a substrate in the vacuum chamber; a high-frequency power supply capable of supplying a high-frequency power to the substrate electrode or a plasma source; and an adhesive sheet, which is disposed on a surface of the substrate electrode and on which the substrate is placed.
 17. A plasma processing apparatus comprising: a substrate mounting station for placing a substrate on a tray having a surface provided with an adhesive sheet; a vacuum chamber; a gas supply unit for supplying gas into the vacuum chamber; an exhausting unit for exhausting interior of the vacuum chamber; a pressure-regulating valve for controlling the interior of the vacuum chamber to a specified pressure; a substrate electrode for placing thereon the tray in the vacuum chamber; and a high-frequency power supply capable of supplying a high-frequency power to the substrate electrode or a plasma source.
 18. The plasma processing apparatus as claimed in claim 16, wherein the adhesive sheet has a thermal conductivity of not smaller than 0.1 W/m·K.
 19. The plasma processing apparatus as claimed in claim 16, wherein the adhesive sheet has Asker C of not greater than
 80. 20. The plasma processing apparatus as claimed in claim 16, wherein the adhesive sheet has a hardness of 50 to
 60. 21. The plasma processing apparatus as claimed in claim 16, wherein the adhesive sheet has a thickness of 0.05 to 0.5 mm.
 22. A tray for plasma processing used for plasma processing for processing a substrate or a film on the substrate, comprising: an adhesive sheet disposed on a surface on which the substrate is placed.
 23. The tray for plasma processing as claimed in claim 22, comprising: another adhesive sheet disposed on a surface opposite from the surface on which the substrate is placed.
 24. The tray for plasma processing as claimed in claim 22, wherein the adhesive sheet has a thermal conductivity of not smaller than 0.1 W/m·K.
 25. The tray for plasma processing as claimed in claim 22, wherein the adhesive sheet has Asker C of not greater than
 80. 26. The tray for plasma processing as claimed in claim 22, wherein the adhesive sheet has a hardness of 50 to
 60. 27. The tray for plasma processing as claimed in claim 22, wherein the adhesive sheet has a thickness of 0.05 to 0.5 mm. 